From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 38049C64EB8 for ; Thu, 4 Oct 2018 09:45:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0464A2098A for ; Thu, 4 Oct 2018 09:45:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0464A2098A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727675AbeJDQiY (ORCPT ); Thu, 4 Oct 2018 12:38:24 -0400 Received: from foss.arm.com ([217.140.101.70]:33538 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727046AbeJDQiY (ORCPT ); Thu, 4 Oct 2018 12:38:24 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6936E7A9; Thu, 4 Oct 2018 02:45:56 -0700 (PDT) Received: from queper01-lin (queper01-lin.Emea.Arm.com [10.4.13.27]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4C0003F5D3; Thu, 4 Oct 2018 02:45:52 -0700 (PDT) Date: Thu, 4 Oct 2018 10:45:47 +0100 From: Quentin Perret To: Peter Zijlstra Cc: rjw@rjwysocki.net, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, gregkh@linuxfoundation.org, mingo@redhat.com, dietmar.eggemann@arm.com, morten.rasmussen@arm.com, chris.redpath@arm.com, patrick.bellasi@arm.com, valentin.schneider@arm.com, vincent.guittot@linaro.org, thara.gopinath@linaro.org, viresh.kumar@linaro.org, tkjos@google.com, joel@joelfernandes.org, smuckle@google.com, adharmap@codeaurora.org, skannan@codeaurora.org, pkondeti@codeaurora.org, juri.lelli@redhat.com, edubezval@gmail.com, srinivas.pandruvada@linux.intel.com, currojerez@riseup.net, javi.merino@kernel.org Subject: Re: [PATCH v7 08/14] sched/topology: Disable EAS on inappropriate platforms Message-ID: <20181004094545.ajkpxmvabfgbdy3y@queper01-lin> References: <20180912091309.7551-1-quentin.perret@arm.com> <20180912091309.7551-9-quentin.perret@arm.com> <20181003162719.GB19252@hirez.programming.kicks-ass.net> <20181004091046.7nn2odqrjy7tp5vx@queper01-lin> <20181004093848.GM19272@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181004093848.GM19272@hirez.programming.kicks-ass.net> User-Agent: NeoMutt/20171215 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 04 Oct 2018 at 11:38:48 (+0200), Peter Zijlstra wrote: > On Thu, Oct 04, 2018 at 10:10:48AM +0100, Quentin Perret wrote: > > On Wednesday 03 Oct 2018 at 18:27:19 (+0200), Peter Zijlstra wrote: > > > On Wed, Sep 12, 2018 at 10:13:03AM +0100, Quentin Perret wrote: > > > > @@ -288,6 +321,21 @@ static void build_perf_domains(const struct cpumask *cpu_map) > > > > goto free; > > > > tmp->next = pd; > > > > pd = tmp; > > > > + > > > > + /* > > > > + * Count performance domains and capacity states for the > > > > + * complexity check. > > > > + */ > > > > + nr_pd++; > > > > + nr_cs += em_pd_nr_cap_states(pd->obj); > > > > + } > > > > + > > > > + /* Bail out if the Energy Model complexity is too high. */ > > > > + if (nr_pd * (nr_cs + nr_cpus) > EM_MAX_COMPLEXITY) { > > > > + if (sched_debug()) > > > > + pr_info("rd %*pbl: EM complexity is too high\n ", > > > > + cpumask_pr_args(cpu_map)); > > > > + goto free; > > > > } > > > > > > I would make than an unconditional WARN, we do not really expect that to > > > trigger, but then it does, we really don't want to hide it. > > > > OTOH that also means that some people with big asymmetric machines can > > get a WARN message every time they boot, and even if they don't want to > > use EAS. > > > > Now, that shouldn't happen any time soon, so it's maybe a good thing if > > we get reports when/if people start to hit that one, so why not ... > > Right, and if becomes a real problem we can think of a solution (like > maybe a DT thingy that says to not use EAS, or a 'better' EAS > algorithm). That works for me. I'll switch to a plain WARN in v8. Thanks, Quentin